1. Field of the Invention
The present invention relates to vehicle cruise control systems for allowing a driver of a vehicle to maintain a set speed without using the accelerator, and more particularly to a cruise control system which responds to a target ahead of the vehicle by reducing the speed entered into the cruise control system by the driver to prevent overtaking the target.
2. Description of Related Art
Cruise control systems for vehicles, such as automobiles, are well known. Such systems enable the driver of the vehicle to enter a desired speed into the system. Thereafter, the vehicle maintains the speed without the need for the driver to use the accelerator. The cruise control system maintains the speed by adjusting the throttle of the vehicle as necessary.
Cruise control systems are desirably and most safely used in conditions of light traffic. Accordingly, such systems are most effectively used in rural settings or other conditions characterized by light traffic, so that the system can be allowed to maintain speed for reasonable periods of time without interruption. Most cruise control systems allow the driver to disengage the system by turning off the control switch for the system or by pressing the brakes of the vehicle. Some more sophisticated cruise control systems allow the driver to reduce the speed of the vehicle from the entered speed by manipulating the controls for the system, and then resuming the entered speed by again manipulating such controls.
In driving conditions which involve heavier traffic, a driver often finds it necessary to frequently disengage or adjust the cruise control system, such as when overtaking another vehicle in the path of the driver's vehicle. This often results in the driver having to turn off the cruise control system and resume manual control of the vehicle's speed. Failure to turn off the cruise control system may pose safety problems, such as where the driver fails to disengage or adjust the cruise control system when rapidly approaching a much slower vehicle in the path of the driver's vehicle.
Accordingly, it would be desirable to provide a cruise control system capable of automatically responding to another vehicle or other target ahead of the vehicle by automatically reducing the vehicle speed by an appropriate amount, without the need for driver involvement. Such a system would also desirably be capable of determining when the vehicle is no longer closing on the target, such as when the target moves out of the path of the vehicle or speeds up, so that the vehicle speed can again be increased and the speed originally entered by the driver eventually resumed where possible. Such a cruise control system would enable the operator to safely use such system in conditions of moderate traffic as well as in conditions of light traffic.